This application is related to steering mechanisms for zero turn radius (ZT) vehicles. Such mechanisms have generally relied upon a pair of individual controls to control two individual transmissions or transaxles for steering. Steering has also been accomplished with a steering mechanism and mechanical linkages. However, these mechanisms are complex and present challenges, especially in the area of control.
ZT vehicles, such as riding mowers with independent front caster wheels, have been known to experience downhill drift during side-hill traverses requiring operators to exact disproportionate power outputs from the downhill transmission to maintain straight line tracking. Front wheel steering, in combination with the steering provided by the independent transmissions, has been known to improve side-hill performance in ZT vehicles but has often compromised the vehicle's zero-radius turn capability. Mechanical coordination of such front wheel steering with that provided by the independent action of the transmissions further increases the complexity of the steering linkages and the resultant control issues. The need exists for a simpler, more exacting front steering apparatus, one that delivers true zero-radius turn capability in coordination with that produced by the drive system of a ZT vehicle; an apparatus preferably packaged for ready integration by manufacturers of such vehicles, who, as a norm, purchase their drive system components.